"Rapid exchange"-type balloon dilatation catheters are catheters which are capable of advancement into the vascular system of a patient along a preemplaced guidewire for balloon angioplasty or the like, in which a guidewire extension unit is not needed in order to remove the catheter without dislodging the guidewire. For example, in one type of rapid exchange catheter, the guidewire occupies a lumen of the catheter in only a distal portion thereof. With respect to the catheter proximal portion, the guidewire exits from the internal catheter lumen and extends along the side of the catheter, being typically retained in that position by a guiding catheter in which both the catheter and the guidewire are contained. Examples of catheters of this general type include those disclosed in Horzewski et al. U.S. Pat. No. 4,748,982; Bonzel U.S. Pat. No. 4,762,129; and Yock U.S. Pat. No. 5,040,548.
Such catheters permit one to replace the catheter without the use of a guidewire extension, which provides a more rapid exchange.
A disadvantage of such "rapid exchange" type catheter systems having a lateral aperture between the ends is that the guidewire cannot be removed for exchange while the catheter is indwelling in the patient. Furthermore, the reduced length of engagement between the guidewire and catheter can compromise the handling characteristics of the catheter. Likewise, the guidewire lumen of such catheters cannot be easily flushed with fluids to clear out obstructions and the like because of the side aperture.
In the conventional, over-the-wire intravascular catheter, the guidewire itself is easily exchanged after the catheter has been inserted. Also, the guidewire lumen is easily flushed with fluids in such a catheter design. However, this design does exhibit the disadvantage of generally requiring the attachment of a guidewire extension unit if one wishes to exchange the catheter.
By this invention, a catheter is provided which exhibits the advantages of the over-the-wire mode of operation, being suitable for use as a "guiding catheter", which is a conventional type of catheter used in angioplasty to receive both guidewire and a balloon catheter within its lumen. While the advantages of the over-the-wire catheter systems may be achieved, internal or balloon catheters may also be exchanged without a guidewire extension, and the guidewire itself may be exchanged with great ease.
Thus, the catheter of this invention can greatly facilitate intravascular procedures that utilize a catheter, particularly angioplasty procedures in which the catheter of this invention is used as the guiding catheter.